50
Instantaneous overcurrent
An overcurrent function without an intentional operating time delay in its instantaneous application.
Protection functions
Protection functions · 50R
Calculated residual instantaneous overcurrent
Supervises an instantaneous residual-current element calculated from phase-current measurements in the cited Eaton family.
SLD / Schematic · 50R
What it represents
Supervises an instantaneous residual-current element calculated from phase-current measurements in the cited Eaton family.
The drafting record should connect this function to the phase CT inputs used to calculate residual current, then trace the calculated residual element and earth-fault trip output. Keep the complete designation and equipment tag together so that the SLD, relay logic and terminal schedule describe the same implementation.
The cited mapping is a public manufacturer example (Eaton EMR family). Suffixes are not universal equivalences across products, and this reference supplies neither a protection setting nor certification of the selected scheme.
How to read it
- Identify the phase CT inputs used to calculate residual current.
- Trace the calculated residual element and earth-fault trip output.
Information to show or reference
- Label the phase CT inputs used to calculate residual current.
- Cross-reference the calculated residual element and earth-fault trip output.
- Retain the complete suffix, selected device tag and manufacturer manual revision.
A distinction that matters
Eaton's R mapping means calculated residual current; a separate measured residual input is identified as X in the same family.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
EMR motor protection: public function comparison
Public primary-source function or application mapping used to identify this designation; wording and drafting notes are original.
IEEE C37.2-2022: power-system device function numbers
Device-number and suffix convention. This page is not a reproduction of the full licensed standard.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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